The term is used to describe experiences related to environmental crises. This definition links eco-anxiety to a general concern, fear or anxiety, mainly related to the belief that the ecological basis of the system is about to collapse.

The most prevalent form of eco-anxiety would appear to be climate anxiety, thus linked to the understandable severity of the ecological crisis, triggered by the concatenation of extreme events (heat waves, water bombs...) and their consequences on the ground (prolonged droughts, floods, fires, desertification, loss of biodiversity...) and in society (food and water insecurity, economic instability, forced migrations...).